1. Field of the Invention
The present invention relates to digital telecommunications systems, and particularly to time division multiplex switching systems for routing voice and data between a variety of telecommunications devices.
2. Description of the Related Art
The integration of computer technology and distributed data processing with telecommunications networks has brought about the evolution of switching technology from basic central offices to call processors, which are capable of handling voice and data communications between a variety of telecommunications devices, as well as over a variety of links, such as lines, trunks and satellite links. This technological evolution has created a demand for a telecommunications system which can provide central office telephone service as well as services associated with customer or local exchange switches such as private branch exchanges (PBXs). Further, a demand has been created for telecommunications networks which are capable of providing expanded services such as call forwarding and voice mail.
To meet these demands, telecommunications systems should ideally be configurable to expand with the size of a communication network. Further, the system should be operable to accommodate different channel characteristics and limitations in order to support services requiring, for example, different bandwidths per channel, and equipment employing different communications protocols. Also, it is desirable to provide users with some means to modify and control the system configuration to selectively increase or decrease the number of ports available, to configure the switch for use with selected telecommunications devices, and to provide selected services to subscribers through a switch without requiring substantial change to the system hardware and software components.
Telecommunications systems have been developed which provide distributed processing for voice and data transmitted by a variety of telecommunications devices. The systems, however, generally must employ compatible telecommunications devices in order to provide many of their telecommunications services. The systems are therefore not fully integrated telecommunications systems. An additional drawback associated with many existing telecommunications systems relates to the lack of modularity of the hardware and software components in the system, making changes in subscriber services and in the number of ports supported by the system uneconomical.